ANIMAL TRANSPORT OCR BIOLOGY

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  • Created by: Davina1st
  • Created on: 18-03-21 10:43
Why do animals need a specialised transport system?
High metabolic demand, as organism gets bigger SA:V gets smaller large diffusion distance, hormones made in one place are needed in another, waste products need to be transported to excretory organs.
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What are some features of a circulatory system?
Liquid transport medium, transport vessels with a pumping system.
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What is a mass transport system?
When substances are transported in a mass of fluid with a mechanism for moving fluid around the body.
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How does an open circulatory system work?
The heart pumps the transport medium into any open cavity. The cavity is called the haemocoel. The transport medium is under low pressure and comes into direct contact with tissues in the body.
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How does a closed circulatory system work?
The transport medium is transported in vessels and does not come into direct contact with cells and tissues. The heart pumps the blood under pressure and substances are exchanged by diffusion.
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How does a single closed circulatory system work?
The blood is pumped once around the whole body before it returns to the heart. It passes through two sets of capillaries. In the first O2 and CO2 is exchanged, then it is exchanged with the organs of the body.
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How does a double closed circulatory system work?
Blood is pumped from the heart to the lungs to pick up O2 and offload CO2, then it returns to the heart. The second loop is blood pumping all around the body and then back to the heart.
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What is the use of elastic fibres in blood vessels?
Can stretch and recoil to provide the walls with flexibility. Composed of elastic
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What is the use of smooth muscle in blood vessels?
Can contract or relax which changes the size of the lumen and therefore pressure.
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What is the use of collage in blood vessels?
Provides structural support to maintain the shape of the wall.
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What is the function of the arteries?
They carry blood away from the heart. The blood is oxygenated except for the pulmonary artery which carries deoxygenated blood from the heart to the lungs/umbilical cord.
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What are arteries composed of, what is each sections function?
Elastic fibres - withstand the force of the blood, can recoil in between contractions fo the heart to even out surges of blood. Collagen for strength and support. Smooth muscle and endothelium cells so blood flows over it with next to no resistance.
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What is the role of arterioles? What are they composed of?
They link arteries to smaller capillaries. More smooth muscle and less elastic fibres. Can construct or dilate to control blood flow to specific organs.
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What is vasoconstriction?
When smooth muscle in the arterioles constructs to prevent blood flowing into the capillary bed.
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What is vasodilation?
When the smooth muscle relaxes and blood flows into the capillary bed.
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What are capillaries? How are they structured?
Blood vessels that link arterioles with venules. Lumen is very small and blood entering is oxygenated and by the time it leaves it has less oxygen and more carbon dioxide.
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How have capillaries adapted to carry out their function?
Large SA for diffusion, walls are only one cell thick = short diffusion distance. Cross sectional area of capillaries are greater than arterioles, so blood pressure drops giving more time for exchange to happen.
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What is the function of the veins?
They carry blood from the cells of the body to the heart, they carry deoxygenated blood, apart from the pulmonary vein which carries oxygenated blood from lungs to heart.
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What are very small veins called?
Venules
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What are the two main vessels that carry deoxygenated blood?
Inferior vena cava ( from lower parts of body) and superiors vena cava (from head and upper body)
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What are veins made up of?
Collagen walls, relatively little elastic fibre. Wide lumen and a smooth thin lining of endothelium so blood flows easily.
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What is the role of venules?
They link the capillaries with the veins.
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Deoxygenated blood in the veins must be returned to the heart to be pumped to the lungs and oxygenated again. It is under low pressure and against gravity. How is it adapted to overcome this problem?
Veins have one way valves, to stop backflow of blood. Bigger veins run in between active muscles, when they contract the veins are squeezed forcing the blood towards the heart. Breathing movements of the chest act as a pump.
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Plasma makes up __% of the blood by volume ?
55%
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What is plasma?
Yellow liquid in blood, carries dissolved glucose, amino acids, mineral ions, hormones and fibrinogen. Transports red blood cells and carries platelets.
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What are platelets?
Fragments of large cells called megakaryocytes found in bone marrow and are involved in the clotting mechanism of the blood.
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Give 4 functions of the blood
Transport of: O2 and CO2 to and from repsiring cells, digested food from small intestine, chemical messages (hormones), platelets to damaged areas. Homeostasis
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What is tissue fluid composed of?
The same as plasma, minus the red blood cells and plasma proteins.
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Describe the movement of water in/out of capillaries
As blood moves through capillaries towards the venous system, hydrostatic pressure falls but oncotic pressure remains constant. However it is still higher than hydrostatic pressure, so water moves back into the capillaries.
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What is lymph?
The tissue fluid that doesn’t return to the capillaries, it drains into blind ended tubes called lymph capillaries.
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What is lymph composed of?
Less oxygen and fewer nutrients than plasma and tissue fluid. Contains fatty acids
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What is the role of the lymph nodes?
They are found along the lymph vessels, lymphocytes build up in the lymph node and produce antibodies when necessary. Lymph nodes also intercept debris and phagocytes.
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How are erythrocytes adapted to carry out their function?
They have a biconcave disc shape - maximum haemoglobin absorption. No nucleus, contain haemoglobin which binds reversible to O2
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What is the equation for haemoglobin forming oxyhemoglobin?
Hb + 4O2 —> Hb(O2)4
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How do erythrocytes carry oxygen/bind to oxygen?
Erythrocytes Exeter capillaries in lung where oxygen concentration is low=steep concentration gradient. Oxygen moves into erythrocytes and binds to haemoglobin. Molecule changes shape=easier for other o2 to join.
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What is it called when the erythrocytes changes shape?
Positive cooperativity - erythrocytes changes shape to make it easier for the next o2 molecules to join.
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Describe the oxygen dissociation curve and what it shows?
Percentage saturation haemoglobin plotted against the partial pressure of oxygen. Shows the affinity of haemoglobin for oxygen. The curve levels out at the top.
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Why does the curve level out at the top?
Highest partial pressure of oxygen, and all haem groups are bound to oxygen, so the haemoglobin is saturated and cannot take up any more.
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What is the name given to the change of partial pressure due to an increase of carbon dioxide?
Bohr shift/effect shows to the left of the dissociation curve.
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Describe and explain the Bohr shift
As partial pressure of CO2 rises, haemoglobin give up oxygen more easily.
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Why is the Bohr effect important in the body?
As a result: in active tissues with high partial pressure of CO2 haemoglobin gives up oxygen more easily. In the lungs where amount of CO2 in the air is low, oxygen binds to haemoglobin molecules easily.
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Why does feral haemoglobin have a higher affinity for oxygen than adult haemoglobin?
Dependant on mother to supply oxygen, oxygenated blood in mother runs close to deoxygenated blood in placenta. Higher affinity means it removes oxygen from the maternal blood as it moves past one another.
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What are the three ways CO2 is transported around the body?
5% is dissolved in the plasma, 10-20% is combined with amino acid groups of the polypeptide chain of haemoglobin to form carb amino haemoglobin. 75-85% are converted into hydrogen carbonate ions in the cytoplasm of red blood cells.
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What is the reaction between CO2 and H2O?
CO2 + H2O —> H2CO3 —> (H+) + HCO3- REVERSIBLE
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What is the role of carbonic anhydrase?
Catalyses the reaction between CO2 and H2O, in cytoplasm of red blood cells, otherwise the reaction occurs very slowly.
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What is the chloride shift?
HCO3- ions move out of erythrocytes into plasma by diffusion down a concentration gradient. And negatively charged CL- ions move into the cell to maintain the electrical balance of the cell.
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What is the role of haemoglobin in erythrocytes? (Transport of chlorine)
Acts as a buffer and prevents changes in pH by accepting free hydrogen ions in a reversible reaction to form haemoglobonic acid
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What is the heart?
Organ that moves blood around the body, it’s complexity changes depending on the mammal.
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Why is the left side of the heart muscle thicker?
Has to pump blood all around the body, not just to lungs like the right side of the body. Thicker walls=more pressure=further distance pushed.
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What muscle is the heart made of?
Cardiac muscle
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What is diastole?
Th pe heart relaxes, the atria and then the ventricle fill with blood, volume and pressure inside heart increase, but decreases in arteries.
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What is systole?
Atria and then the ventricles contract, blood pressure in arteries is at a maximum.
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How does the heart sound through a stethoscope?
‘Lub-dub’ first sound is as the blood is forced against the AV valves as ventricles contract. Second is from back flow of blood against semilunar valves.
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What does myogenic mean? Is the cardiac muscle of the heart myogenic?
Cardiac muscle is myogenic, it has its own intrinsic rhythm so that resources aren’t wasted by maintaining a heartbeat.
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How does the heart conduct a heartbeat?
SAN starts excitation causing atria to contract, impulse passed to ventricle, AVN sends impulse to bundle of His and purkyne fibres after delay, then to apex which triggers ventricular systole.
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Why is there a delay before the AVN sends the impulse?
To ensure the atria have stopped contracting before the ventricles start.
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What is an ECG?
Electrocardiogram- measure tiny electrical differences in your skin that result from the electrical impulse of the heart.
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What is tachycardia?
Very rapid over 100bpm, can be treated by medicine.
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What is bradycardia?
Slow below 60bpm may need an artificial pacemaker.
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What is an ectopic heartbeat?
Extra heartbeats out of the normal rhythm.
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What is atrial fibrillation?
Abnormal beating, including rapid and slow heart beats.
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What is the role of the SAN (Sino-atrial node)?
Pacemaker of the heart - initiates heartbeat by electrical impulse which causes atria to contract followed by ventricles after a delay.
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What is the role of the purkyne fibres?
Conducting tissue, allow the electrical impulse to flow through the septum.
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What is the role of the atrioventricular node? AVN
Ensures there is a delay before the electrical impulse is passed on
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Card 5

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